Magnetic separator and the process of separation



Jan. 12, 1937 R. H. STEARNS MAGNETIC SEPARATOR AND THE PROCESS OF SEPARATION Filed 001;. 5, 1951 5 Sheets-Sheet l Jan. 12, 1937. R. H. STEARNS MAGNETIC SEPARATOR AND THE PROCESS OF SEPARATION Filed Oct. 5, 1951 3 Sheets-Sheet 2 Jan. 12, 1937. R STEARNS 2,067,584

MAGNETIC SEPARATOR AND THE PROCESS OF SEPARATION FiLed- Oct. 5, 1931 5 She ets -Sheet I;

Patented Jan. 12, 1937 MAGNETIC SEPARA'IOR AND THE PROCESS OF SEPARATION Roswell H. Stearns, Milwaukee, Wis., assignor to Magnetic Manufacturing Company. Milwaukee,

Application October 5, 1931, Serial No. 566,885 21 Claims. (01. 209-218) This invention relates to magnetic separators and to the process of separation. In magnetic separators as heretofore constructed it has been the usual practice to separate the magnetic particles from the non-magnetic material. With the separators heretofore constructed it has been diflicult to produce a separator which would even inefliciently separate magnetic material to a point where the remaining amount of the magnetic material approximated a negligible value. Even where a very great separation was attained, it was found that the loss of the non-magnetic material was excessive and consequently the process was, from a practical point of view, almost prohibitive.

lhis invention is designed to overcome the defects noted above, and objects of this invention are to provide a novel form of magnetic separator and a process of separation which will reduce the magnetic content to a very low value without an appreciable loss of the non-magnetic material.

In the usual processes followed for the magnetic separation it has been the practice to remove the magnetic material from the nommagnetic material and ithas been found with these processes that a considerable amount of the non magnetic material was removed with the mag netic material, so that if a high degree of separation was attained, a great loss resulted in the non-magnetic material.

Further, it has been found that diificulty was experienced in the separation, as material ground to a finely divided state, tends to agglomerate causing irregular feeding, and when distributed to carrier means .for separation readily adheres to the same, seriously interfering with the separation of the particles. The loss, under these conditions, of the non-magnetic material was very high and the separation very diflicult.

Further objects of this invention are to provide a magnetic separator and a process of separation in which the non-magnetic material is separated from the magnetic material thereby reversing the usual steps in the separation as heretofore commonly employed, and to provide a separator which although capable of handling difierent forms of material is nevertheless eminently suited to the separation of very finely powdered, non-magnetic material from similarly finely powdered magnetic material, or, in fact, from magnetic material of any form.

Further objects are to provide a magnetic separator in which the mixture of the magnetic and -of one form of magnetic separator.

non-magnetic material is passed through a screen formed of magnetic material, such, for example, as soft iron, and is held in a very strong magnetic field so that the finely powdered, non-magnetic material will pass through 5 the screen, whereas the magnetic material will actually contact with and adhere to the screen, the benefit being taken of the fact that where magnetic material contacts with the magnetized screen, that a very secure holding of the mag- 10 netic material is secured, as distinguished from the lifting or removal of the magnetic material from the non-magnetic material.

Further objects are to provide a novel form of separator in which highly eillcient means are 5 provided for insuring the passage of the nonmagnetic material directly through the screen and for the subsequent removal of the adhering magnetic material from the screen.

Further objects are to provide a magnetic separator which has a high capacity, which will reduce the iron content or magnetic content to a very low value far below that customarily obtained in the usual practice, and to provide an apparatus which will remove the magnetic ma- 25 terial, although the magnetic material may be a very small percent of the body of the material fed the separator, that is to say, which will efficiently operate upon a mixture of a very small percent of magnetic material and a very large percent of non-magnetic material without an appreciable loss of the nonmagnetic material. Embodiments of the invention are shown in the accompanying drawings, in which:-

Figure 1 is a side elevation, partly in section, Figure 2 is an end view of the structure shown in Figure 1.

Figure 3 is an enlarged fragmentary plan view of a portion of the magnetic belt or traveling screen.

Figure 4 is a fragmentary sectional view through the traveling screen or belt.

Figure 5 is a view of a modified form of separator. Referring to Figures 1 to 4, it will be seen that the separator comprises a pair of rollers I and 2 upon which the endless magnetic screen or belt 3 is carried One of the rollers, for instance the roller l, is driven through suitable reduction mechanism, such as indicated generally at 4, by means of an electric or other motor 5. Preferably one of the pulleys or rollers, for instance the roller 2, is adjustable to take up slack in the belt.

Means are provided for rapidly agitating the upper stretch of the belt or endless screen I, and other means are.. provided for less rapidly though more violently agitating the lower stretch of the belt. The upper agitating means may consist of a hexagonal roller 6 bearing against thebelt and rapidly driven by meansof the traveling belt, thereby causing the belt to rapidly vibrate, in fact at such a rate in actual practice as to produce a bum. The lower agitator con; sists of a rectangular roller 1 which is preferably covered by means of a rubber. sheath 8. The lower roller having less faces than the upper roller, vibrates the lower stretch of the,

belt less frequently though more violently than the upper roller.

Immediately above the upper stretch of the belt an inducing magnet is positioned. This magnet may consist of a pair of longitudinally extending pole pieces 9 Joined by means of a' single or aplurality of cores it, each of which carries an exciting winding ll. Thus the longitudinally extending pole pieces 9 are positioned immediately above the upper stretch of the belt and consequently the belt or endless screen 3 is in a very strong magnetic field and consequently is highly magnetized. The lower stretch of the endless screen is substantially out of the magnetic field, as will be immediately appreciated from reference to Figure 1 of the draw- A hopper l2 leads downwardly and slantingly towards the upper stretch of the belt and terminates in proximity to such belt or endless screen. The powdered material is placed in the hopper and feeds downwardly upon the traveling screen or belt and is removed by the motion of the belt below the hopper, Obviously, any suitable means of feed could be employed, although from actual practice, .it has been found that this type' of feed is highly satisfactory.

Below the upper stretch of the belt or screen a collecting hopper I3 is positioned and it is pref-, erable though not necessary to divide this hopper into two sections, as shown in Figure 2, so that the-non-magnetic material will discharge 'to opposite sides of the machine and a. relatively steep slant for the hopper is obtained; A second hopper or lower hopper ,is positioned below the lower stretch of the belt and may have a central discharge space. This lower hopper is designed to collect the magnetic material.

The mechanism is preferably carried by means of a metal frame work, indicated generally at l6, which is of open work construction and provides free access to all of the parts of the separator. v Referring to Figures 3 and 4, it will be seen that the magnetic screen or belt 3 consists of a plurality of links of soft iron wire preferably formed in successive convolutions and held together in any suitable manner, as by means of the transverse pins IS. The belt or endless! screen is formed, as stated, of soft iron or other magnetic material, so that it is readily highly magnetized when it passes into the strong magnetic zone and is readily demagnetized when it passes from such zone. 1

It is to be noted in this connection that the belt has open spaces between successive meshes so that the non-magnetic material may pass freely through the belt while the belt is in the intense magnetic field. The upper agitator 6' keeps thebelt-constantly rapidly vibrating so that the non-magnetic material sii'ts th o the belt or endless screen substantially all portions of the mixture of magnetic and non magnetic material contacts at one time or another with the portionsof the belt. By forming the belt relatively thick, as shown in Figure 4, it is possible to secure a somewhat double action, that is to say, .to provide both upper and lower portions of each link or convolution, so that an additional chance of contactis aflorded the magnetic material with the portions of the endless screen.

The inductibly magnetized screen shown and described in detail is commonly known in the trade as a woven screen. It is so flexible about lines at right angles to its length that it may be wrapped about a very small cylinder with the utmost freedom. It is relatively ri id transversely primarily due to the transverse coupling rods or wires It. These features render this belt eminently satisfactory in the novel combination disclosed. For example, it may be very freely agitated; it may be freely bent aroundpresents an enormous surface area of the ingglctibly magnetized iron wires composing the t. 1 l The endless screen has a substantial amount of body and consequentLv a large amount of magnetic flux may be carried by the screen, thus insuring adhermce of the magnetic material to the portions of the screen. The rapid vibration of the screen by means of the upper agitator insures the free passage of the finally divided, non-magnetic material through the screen. The machine actually has a very high capacity, although securing a-separation of a remarkable degree.

The endless. screen passes around the pulley or roller I out of the magnetic held and the clinging particles of magnetic material are removed from the lower stretch of this endless screen or belt by the lower agitator I. This lower agitator gives the lower stretch of the belt a relatively rapid vibration, though preferably of a lesser rate than that imparted to the upper the lower stretch of the belt considerably more violently than the upper agitator.

It is to be noted inthis connection that it is a well known fact that where magnetic material clings to other magnetic material, that it is necessary to give a blow orsharp impact in order to cause the separation of the clinging magnetic material. Thisis accomplished by the relatively more violent blows struck the lower stretch of the belt by the lower agitator. In other words, any tendency for magnetism to remain either in the adhering particles or in the lower stretch of the belt is avoided by actually striking the lower stretch of the belt rapid and relatively hard blows.

It has been fo md that the rubber sheath 8 around the rectangular lower agitator is somewhat rounded at the corners, and also it has been found that it clings better to the lower stretch of the belt. Although the lower agitator action between the rubber sheath 8 and the lower stretch of the belt. The upper agitator sheaths, although if desired, such sheath could be added. In addition to this, it is obvious that the exact shape or the exact construction of the' agitator may be varied.

In actual operation of this apparatus it has been found that the separator will emciently and rapidly operate upon very fine powderedmaterial containing as low as .25 of 1% of magnetic material, and will reduce this magnetic content to as low as .005 of 1% of magnetic material. This remarkably low reduction in magnetic content is obtained without an appreciable loss of the non-magnetic material.

The invention may take other forms, one of which is illustrated in Figure 5.

In this form of the invention the same principle is employed, namely, the non-magneticmaterial is removed from the magnetic material while the magnetic material is in an intense magnetic zone. In this form of the invention the endless screen is indicated by the reference character l1 and is carried by an upper roller I8 and a pair of lower rollers l9 and 2%, an intermediate roller 2i being provided for the lower stretch of the belt. The roller I9 is carried within a lower hopper 22, which is provided with a drain pipe 23. The material is supplied from a hopper or open top tank 24, which in turn is constantly replenished by means of a supply pipe 25.

In this form of the invention the finally divided material is fed in a stream of water or other liquid to the separator. Preferably an agitator or paddle 26 is positioned in the lower portion of the supply tank 24. The liquid flows out of the tilted supply tank 26 carrying the suspended mixture of magnetic and nonmagnetic material, over on to the upwardly traveling stretch of the belt or endless screen.

This screen passes adjacent the longitudinally extending poles 21 of the electromagnet and is consequently highly magnetized. The upwardly traveling stretch of the belt in this magnetic zone also passes between the side plates 28 and over the slanting baflles 29. In reality the flow of the liquid carrying the material is roughly as indicated by the curved arrows in Figure 5, and it will be seen that this material carrying liquid passes back and forth through the screen a number of times before it is discharged into the discharge hopper 22 for the non-magnetic material and liquid.

It is preferable to form the shield plates 28 and the bafiles 29 as well as the bottom portion of the trough 30 of non-magnetic material.

It is also preferable in both forms of the invention to have the pulley or roller over which the belt passes in leaving the magnetic zone somewhat closely positioned with respect to the pole pieces. For example, in Figure 5 the intermediate pulley 2| is close to the upper edges of the pole pieces 21, and in Figure l the pulley l is close to the rear ends of the pole pieces 9. Thus the pulleys over which the endless screen passes in leaving the magnetic zone are somewhat within the infiuence of the magnets with the result that the endless screen in passing over these pulleys is not yet demagnetized.

In the form shown in Figure 5 the pulley 20 is located in the collecting hopper 3| for the magnetic material. washed ofi from the belt by means of the passage of the belt through the liquid, such as the water in the hopper 3|,the water in the hopper being maintained by means of a constant spray The magnetic material is from the spray pipe 82 and overflowing through the overflow port 33.

A discharge pipe 34 is provided for the lower portion of the hopper 31' and whenever it is desirable the valve controlling such pipe may be opened and the relatively heavily loaded l. quid carrying the magnetic material may be discharged. Similarly, a hand valve is preferably provided in the pipe 23, although normally the pipe 23 is left open.

It is to be noted that the spray pipe 32 with its nozzles directs streams of water slantingly downwardly upon the upwardly traveling portion of the screen or belt I! and wash any adhering magnetic particles from such belt. The major portion of the magnetic particles, however, are washed from the belt by its passage downwardly into and upwardly through the liquid in the tank or hopper 3|.

It will be seen that a novel form of magnetic separator has been provided by this invention which although producing a very desirable result and fulfilling an urgent demand, is nevertheless of relatively simple and reliable construction and may be readily produced by-ordinary machine shop processes.

It will be seen further that the separation is accomplished and carried to a very high degree without an appreciable loss of the non-magnetic product.

It will be seen further that a novel method of operation has been provided whereby .the non-magnetic material is removed from the magnetic material, thus reversing the usual steps in the process and securing a far better result.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

l. A magnetic separator comprising an endless screen formed of magnetic material,- a pair of spaced drums upon which said member is can'ied, means for driving one of said drums, means feeding material upon one stretch of said endless screen, means for magnetizing such stretch of said screen to cause the magnetic material to cling to such stretch while the nonmagnetic material passes therethrough, and a polygonal roller across which the other stretch of said screen passes, whereby the rotation of said roller vibrates the last mentioned stretch of said screen to remove the magnetic material therefrom.

2. A magnetic separator comprising an endless screen formed of magnetic material, a pair of spaced drums upon which said member is carried-means for driving one of said drums, means feeding material upon one stretch of said endless screen, means for magnetizing such stretch of said screen to cause the magnetic material to cling to such stretch while the nonmagnetic material passes therethrough, a. polygonal roller across which such stretch passes for vibrating said stretch to remove the non-magnetic material, and a polygonal roller across which the other stretch of said screen passes, whereby the rotation of said roller vibrates the last mentioned stretch of said screen to remove the magnetic material therefrom.

'3. A magnetic separator comprising an endless screen formed of magnetic material, a pair of spaced drums upon which said member is can'led. meansfor driving one of said dr ms. means feedingmaterial upon one stretchof said endless screen. means for magnetizing such stretch of said screen to cause the magnetic material; to cling to such stretch while the nonmagnetic material passes therethrough, a polygonal roller across which such stretch passes for vibrating said stretch to remove the non-magnetic material, and a polygonal roller across which theother stretch of said screen passes. whereby the rotation of said roller vibrates the last mentioned stretch of said screen to remove the magnetic material therefrom, the first mentioned roller giving said screen a more rapid vibrating motion of less amplitude than said second mentioned roller.

4. In combination, a magnetic separator comprising a primary and a secondary magnet, said primary magnet consisting of two poles of magnetic material in spaced relation having extended faces, a series of cores oi magnetic ma-' terial, 'a series or electrical coilwindings aroundsaid cores in assembled relation, said cores being in a parallel plane and having said poles.attached thereto and extending downwardly; and at right angles to said cores, said .primary magnet having a horizontal magnetic field, the sec.- ondary magnet comprising a horizontal flexible woven wire screen belt'formed of magnetic material having mesh openings and mounted on drums for continuous travel in and out between the poles and field of said primary magnet, in the plane of said" horizontal field, and parallel to the extended faces of the poles and at right angles to the said poles.

5. In combination, a magnetic separator comprising a fixed primary magnet having extended poles producing afield extending in approximately a plane from pole to 'pole, asecondary magnet comprising a moving flexible woven screen belt of magnetic material adjacent and at right angles to the extended poles of said primary magnet and having an active portion lying within the plane or said magnetic field, means for causing said belt to travel into and out of the field of said primary magnet, said primary magnet being used only to inductively magnetize said secondary magnet in its travel in andout of said primary magnetic field.

6. In combination, a magnetic separator comprising a fixed Pr mary magnet having extended poles producing a field extending in approximately a plane from pole to pole, a secondary magnet comprising a moving flexibly woven screen belt adjacent and at right angles to the extended poles of said primary magnet and having an active portio'rrlying within the plane of said magnetic field, said secondary magnet being inductively magnetized by'short circuiting the magnetic lines or force, between the poles of said primary magnet. 5'

7. A magnetic separator comprising a primary magnet member, a flexible screen formed of relatively movable elements 01' magnetizable' material forming a secondary induced magnetic member, said screen being mounted between the poles of said primary magnet at right angles thereto and with its opposite longitudinal edges adjacent thereto and with its central portion remote from the poles, and forming a natural return path for the magnetic circuit transmary magnet and a secondary, induced magnet,

comprising a flexible screen formed of articuin a parallel plane, in and out of said primary magnetic field with its opposite longitudinal edges adjacent the poles of said primary magnet and with its intermediate portion remote from said poles, whereby said screen is sectionally magnetized by induction. k

9. A magnetic separator comprising a primary magnet and a secondary, induced magnet formed of articulated elements of magnetizable material forming a screen, means for moving said inductively magnetizable screen through the primary magnetic field and at right angles to the poles or said primary magnet with its opposite longitudinal edges adjacent the poles or said primary magnet, at a predetermined speed,'means for discharging a mixture of magnetic and non-magnetic materialthereon, and

means for agitating said screen, whereby the magnetic material will cling to said screen and the non-magnetic material will pass through said screen within the magnetic field.

10. A' magnetic separator comprising an endless fiexible screen formed of relatively movable members of magnetic material, means for producing a magnetic field, means for passing said screen into and out of said magnetic field with the magnetic linesoi force extending transversely across and in the plane 0! said screen at right angles to the line or travel of said screen, means within the magnetic field for supplying said screen with a mixture 'of magnetic and non-magnetic material while said screen is within said magnetic field, wherebythe non-.

magnetic material passes through said screen while within said magnetic field and the magnetic material clings to said screen, and means for removing the magnetic material from said screen when said screen is out of said magnetic field.

11. A magnetic separator comprising a fiexible traveling member formed of intermshi'ng relatively movable members of magnetic material, means for producing a magnetic field into and out of which said member passes with the magnetic lines of force extending transversely across and in the plane of said screen at right angles to the line of travel of said screen, means within the magnetic field for supplying a mixture of magnetic and non-magnetic material to said member, means for removing the non-magnetic material from said member while within said magnetic field, and means for subsequently vfor producing a magnetic field and a traveling magnetic member movable into and out of said field, means within the magnetic field for 'discharging a mixture of magnetic and non-magnetic material upon said member, the lines of force of said field extending transversely across and in the lane 01' said traveling magnetic member and at right angles to the direction of travel of said member, means for vibrating said member while said member is within said field to cause said non-magnetic material to pass through said memberwhile the magnetic material'clings to said member, and means for vibrating said member outside of said field to remove the magnetic material therefrom.

.13. A magnetic separator comprising means for producing a magnetic field and a traveling flexible magnetic member passing into and out of said field, means within the magnetic field for discharging a mixture of magnetic and nonmagnetic material upon said member while said member is within said field, the lines of force of said field extending transversely across and in the plane of said traveling magnetic member and at right angles to the direction of travel of said member, means for vibrating said member while said member is within said field to cause said non-magnetic material to pass through said member while the magnetic material clings to said member, and means for vibrating said member outside of said field to remove the magnetic material therefrom.

14. A magnetic separator comprising an endless screen belt of magnetic material, means for producing a magnetic field, means for passing said screen into and out of said magnetic field, means for supplying a liquid having suspended magnetic and non-magnetic material therein to said screen within said magnetic field and passme said liquid back and forth through said screen a plurality of times while said screen is in said magnetic field, to cause the non-magnetic material to pass from said screen and the magnetic material to adhere to said screen, and means for passing said screen through liquid washing means distinct from said first mentioned liquid for removing the magnetic material adhering to said screen, when said screen is out of said magnetic field.

15. A magnetic separator comprising a screen flexibly formed of intermeshing elements of magnetic material, said screen being in the .form of an endless belt, magnetic means for producing a field transversely across said belt so that the elements of said belt form a path for the magnetic fiux transversely of said belt from element to element and from one longitudinal edge to the other, means for moving said belt to cause said belt to pass through and out of said field and means for feeding a mixture of magnetic and non-magnetic material tosaid belt while said belt is in said field.

16. A magnetic separator comprising a primary magnet member, a fiexible endless screen belt formed or relatively movable elements 'of magnetizable material forming a secondary induced magnetic member, said screen being carried by spaced drums and being mounted between the poles of said primary magnet at right angles thereto and with its opposite longitudinal edges adjacent thereto and forming a natural return path for the magnetic circuit transversely across said screen, one stretch of said screen only between said spaced drums'being magnetized.

- 17. A magnetic separator comprising a primary magnet member, a screen formed of relatively movable elements of magnetizable material and. iorming a secondary induced magnetic member, said screen being bendable along lines transversely of said screen and being relatively rigid in a direction at right angles thereto, whereby sagging of said screen is prevented, said screen being mounted between the poles of said primary magnet and at right angles thereto with its opposite longitudinal edges adiacent thereto and forming a 'natural return path for the magnetic circuit across said screen.

18. A magnetic separator comprising an endless belt 0! magnetic material, means for producing a magnetic field, means for passing said screen into and out of said magnetic field,

means for supplying a liquid having suspended magnetic andnon-magnetic material therein to said screen within said magnetic field and passing said liquid back and forth through said screen a plurality of times while said screen is in said magnetic field to cause the non-magnetic material to pass from said screen and the magnetic material to adhere to said screen, liquid washing means including a tank of liquid, and a spray distinct and separate from said first mentioned liquid for removing the magnetic material adhering to said screen when said screen is out of said magnetic field.

19. The method of separating finely ground magnetizahle from non-magnetizable material consisting in producing a main magnetic field. spreading the material out in a sheet, temporarily supporting the material while spread out in the form of a sheet, and passing the sheet of material through said main magnetic field at right angles to said field with the poles of said field located adjacent the marginal edges of said sheet of material, producing intense local fields at the exact point of separation to hold the magnetizable material at the local intense fields, and moving the said intense local fields at right angles to the main magnetic field, whereby the magnetizable material will be carried out of said main magnetic field, and the non-magnetizable material will drop away at an angle to said main magnetic field while in said main magnetic field.

20. The method of separating finely ground magnetizable from non-magnetizable material, consisting in producing a main magnetic field,

spreading the material out in a sheet, temporarily supporting the material while spread out in the form of a sheet, and passing the sheet of material through said main magnetic field at right angles to said main magnetic field with vthe poles pf said field located adjacent the marginal edges of said sheet-of material and forming local intense magnetic fields at the ,magnetizable from non-magnetizable material comprising producing a main magnetic field,.

spreading the material out in a sheet, temporarily supporting the material while spread out in the form of a sheet, and passing the sheet 0! material at right angles to said main magnetic field and through said main magnetic field, forming a multitude of local intense magnetic fields at the sheet of material with the fiux due to said local intense magnetic fields extending in a multitude of different angular directions to preclude the escape of magnetic material from the material while in the main magnetic field, allowing the non-magnetic material to drop down away from the plane 0! the sheet of material at approximately right angles thereto while in the main magnetic field, and moving the magnetic material held at the local magnetic fields from said main magnetic field.

ROSWELL H. S'I'IARNB. 

